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UNITED STATES PATENT OF ICE.

cEORcE w. GOETZ, OE rrrTsBURc, PENNSYLVANIA, AssIGNOR o THE OREREDUCTION COMPANY, OF SAME PLACE. w

PROCESS OF IEXTRACTING GOLD FROMIOREIS.

SPECIFICATION forming part of Letters Patent No. 416,781, dated December10, 1889.

Application filed March 20, 1889., Serial No. 304,012. (No specimensi Toall whom it may concern.- a health of the workmen which it-occasions. Beit known that I, GEORGE W. GOETZ, a The ordinary present practice is tocharge citizen of the United States, residing at Pittsthe ore into acylinder, together with the burg, in the county of Allegheny and Statechemicals proper for the generation of chlo- 5 of Pennsylvania, haveinvented or discovered 'rine, after which the charging-door is closed acertain new and useful Improvement in and the cylinder rotated for asufficient pe- Processes of Extracting Gold from Ores, 'of riod toeffect the solution of the gold. VYhen which improvement the followingis a specithis has taken place, the contents of'the cylfication. inderare discharged upon a filter-bed having 1o Myinventionrelatestoprocesses of the gena large area for the purpose ofseparating eral classor type known in the art as chlothe solution containing the gold fromthe ore rination, in which the extraction of gold pulp. In the dischargeof the ore upon the from its ores is effected by subjecting the orefilter-bed the free chlorine escapes into the or auriferons gangue tothe action of chlorine working-rooms in such quantities as to cause '15gas, by which the gold is dissolved,and theremuch inconvenience andannoyance to the after precipitating the gold from the solution workmen,delaying an interfering with their and melting it into ingots. work, aswell as being prejudicial to their The object of my invention is toobviate health and comfort, and this is found to be the inconvenienceand deleterious results the case to a greater or-less degree even when20 due to the escape and diifusion of free chlothe gases are exhaustedfrom the cylinder, as rine into the atmosphere adjoining the appafar aspracticable, before Opening the door to ratus in which the operation isconducted, to effect the discharge of its contents, as all which end myinvention, generally stated, solutions containing free chlorine willemit consists in a novel process of treating the strong chlorine vapors,and an excess of chlo- 25 Ore or gangue with a proportion of chlorinerine must be-present in the cylinder in order less than that which willsuffice to extract to hold the gold in solution. I a the entire amountof contained gold, and dis- My improvement is designed to enable thesolving the remaining portion of gold by the process of chlorination tobe eifectively conaction of a proportion of bromine in excess ductedwithout involving the objection above 0 of that sufficient to act as asolvent for such stated.

remaining proportion of gold. 7 In the practice of lnyinvention Isubject i The improvement claimed is hereinafter the pulverized ore, asheretofore, to the acfnlly set forth. tion of chlorine in any suitableclosed vessel;

The processes now known and practiced but, in lieu of generating thereinor supply t 35 for the extraction of gold may be divided ing thereto thechlorine in sufficient quantity generally into those of smelting,amalgamato dissolve all the gold which is present in tion, andchlorination, and, in the case of the ore and to hold the goldinsolution, I many ores a chlorination process is the only treatthe orewith a quantity of chlorine less 1 one which is successfully ordesirably applicathan that which is required for the solution t I 0 ble.In the latter processes the ore is treated of the entire amount of goldcontained there either with free chlorine gas or with a soluin, so thatthere may remain a small proportion saturated therewith, and it isdifficult in tion of undissolved gold, and effect the solu-, most of theapparatus employed and impostion of the remaining proportion of gold bysible in many to prevent the escape of the the action of bromine insufficient quantity, 45 gas from time to time into the building in topresent an excess above that which is rewhich the apparatus is located.This gas bequired to dissolve the small proportion of gold ing of anextremely offensive and irritating remaining undissolved by thechlorine, the character, its presence, even in smallquantiexcess ofbromine being added to prevent the ties, in the atmosphere about theapparatus reprecipitation of the gold, as well as to insure I00 50 isgreatly objectionable by reason of the anthe solution of all which mayremain after noyance to and detrimental eifectupon thethe action of thechlorine, The presence of rine-generating materials and of bromineproper to be employed, ten pounds of bleaching-powder or chloride oflime and fifteen pounds of sulphuric acid may be mingled with a ton ofore of such character that the chlorine evolved from said chemicals willbe sufficient to dissolve, say, eighty-five per cent.

of the gold in the ore, the chlorine generated being thereby entirelytaken up, so that the solution will not give off any odor. By theaddition of about one pound of bromine the remaining fifteen per cent.of gold will be taken up and sufficient bromine will be maintained toremain free in the solution and prevent a reprecipitation of the gold.The solution'not being completely saturated with bromine, no deleteriousf um es will escape from the treating-vessel or from the chargedelivered on the filter-bed, as would be the case it free chlorine werepresent in the solution.

In the practice of my improved process the chlorine may either bebrought in gaseous form to the pulverized ore from a generator in whichit is separately evolved or be generated in contact with the ore fromchemicals added thereto. I prefer to use bleachingpowder (chloride oflime) and sulphuric acid as the chlorine-generating chemicals and to addthe required proportion of bromine in liquid form. v

I claim as my invention and desire to secure by Letters Patent 1. Theimprovement in the art of extracting gold from ores which consists intreating pulverized auriferous ore with a proportion of chlorine lessthan that which is required to effect the solution of the entire amountof gold contained in the ore, and dissolving the remaining portion ofgold by the action of bromine in greater proportion than that which isrequired to effect the solution of said remaining portion, substantiallyas set forth.

2. The improvement in the art of extracting gold from ores, whichconsists in mixing with pulverized au'riferous ore chloride of lime andsulphuric acid in proportion which,

will generate less chlorine than that which will suffice to effect thesolution of the e11- tire amount of gold contained in the ore, and

bromine in greater proportion than that which will suffice to effect thesolution of the proportion of gold remaining undissolved by thegenerated chlorine, substantially as set forth. In testimony whereof Ihave hereunto set my hand.

GEORGE V. GOETZ. Witnesses:

J. SNOWDEN BELL, F. E. GAITHER.

